Capillary electrophoresis (CE) is a well-known technique for separating molecules, compounds, and the like, in a sample with high efficiency. Capillary electrophoresis is generally performed by a CE instrument that introduces a sample comprising analyte molecules of interest to a narrow-diameter capillary. The CE instrument applies a voltage across the length of the capillary, causing electroosmotic and electrophoretic movement of the analyte molecules in the capillary. The analyte molecules are separated, and later identified, according to differences in electrophoretic mobility, molecule size, or other properties.
The CE instrument can be coupled to an analytical instrument, such as a mass spectrometer, that identifies and analyzes complex mixtures and compounds provided in the sample. These configurations generally require an electrospray ionization (ESI) procedure to be performed. ESI produces ions from highly charged liquid droplets comprising the analyte molecules by an electric field produced near the outlet of the capillary. The ionized analyte molecules are subsequently output from the capillary to the mass spectrometer.
Separation and ionization techniques performed in the capillary preferably maximize sensitivity and resolution of the sample, resulting in better detection and analysis by the mass spectrometer.